With the development of communications technologies, users expect not only to use a telephone service on a telephone-enabled device, but also to share the telephone service in a home network. In a Universal Plug and Play (UPnP) telephony standard, three functional entities are defined: Telephony Server (TS), Telephony Client (TC), and Telephony Control Point (TCP). The TS provides telephone services for other devices in a home network. The TC receives data streams from the TS in the home network and presents the data stream information to the user; and/or provides data streams for the TS. The TCP exercises control to implement telephone service sharing between the TC and the TS in the home network. The connection relation between the TC, the TS, and the TCP is shown in FIG. 1. The data streams between the TC and the TS are transmitted through an outband mechanism, and the data streams transmitted between the TC and the TS include media streams and/or short messages.
In the conventional art, the data streams between the TC and the TS are vulnerable to being intercepted or altered by illegal devices, and are not secure.